Process of recovering sulfur.



WILLIAM A. HALL, OF NEW YORK, N. Y.

PROCESS OF RECOVEBING SULFUR.

No Drawing.

Specification of Letters Patent.

Application filed June 25. 1913. Serial N 0. 775,742.

Patented Dec. 30, 1913.

To all 'IlJllOl/b it may concern Be it known that 1, WILLIAM A. IIALL, citize of the United States, residing at New l'ork, in the county of New York and State of New York, have invented or discovered certain new and useful Improve-I ments in Processes of Recovering Sulfur, of which the following is a specification.

In my copending applications Serial Numbers, 725,024, filed Oct. 10, 1912; 770,946, filed May 31, 1913; and 773,450, filed June 13, 1913, I have disclosed certain processes of obtaining sulfur from ores, such as pyrites, pyrrhotite and the like, by distilhng from the ore, at temperatures between 700 and 900 C. by the action of a reducing flame and steam, while agitating said ores.

The present invention contemplates an improvement upon the processes set forth in the above mentioned applications, said improvement comprising the use of a gas mix- .ture containing methane and ethylene, as

the fuel employed, and in operating with these gases it is not ordinarily necessary to admit any steam Whatever, for the reason that the combustion of the hydrogen present in these gases is ordinarily quite suificient to furnish the steam necessary for the reaction.

The present invention contemplates the use of ores without being restricted to ores in which a feeble atom of sulfur exists, such as pyrites, since such ores as pyrrhotite and other metal sulfids may beemployed, although thisprocess can be used, if desired with pyrites, although pure ferrous sulfid FeS, which contains no feeble atom of sulfur whatever, may be employed.

In accordance with the practice of my invention I take a furnace preferably of any well known mechanical type, such as described for instance in my copending application Serial Number 725,023, filed Oct. 10, 1912, (wherein agitation of the ore may be effected) said furnace being heated internally by direct reducing flame produced from the described gas, with air, the amount of air admitted bein so regulated that the flame produced while not necessarily a highly reducing flame, is of sufficient reducing character to combine with any free oxyen and in no case: anoxidizing flame. team, or water which would be formed into steam, may be, if. necessary, passed in through inlets suitably disposed, preferably in larger quantity toward the lower end of the furnace, the furnace being provided with a gas outlet from which extends a long discharge pipe. Into this discharge pipe steam may also be passed with the object hereinafter referred to. When the furnace has been raised to the proper temperature preferably somewhat above 700 C. (the distilling temperature of the sulfur of the ore), and preferably to a temperature near 800 0., but not over 900 C., the ore is led thereinto in a continuous stream with the least admission of air possible.

I find it desirable at all times to maintain a very slight internal pressure in the furnace which is easily accomplished by means of the expanded gases. This prevents ingress of any undesirable excess air.

It is essential that the ore should be agitated to the greatest possible extent while in the furnace. If this were not done much less sulfur would be discharged.

The products of combustion pass up through a long discharge pipe in which the temperature is reduced several hundred degrees and the products of combustion pass out sin-charged with yellow sulfur va or without any appreciable admixture of 0 This fact has been determined by analysis of the gases.

The discharge pipe leads the sulfur vapor and products of combustion to a gas-washing apparatus such as the well known Thiesen apparatus or other gas washer, where the atmosphere is quickly clarified by the precipitation of the finely divided sulfur in the water of the washer and from this it is extracted by any desired means.

The reactions which take place in the interior of the furnace are substantially as follows: 1. A decomposition of the sulfid, and distillation of free sulfur, a very small proportion of which may change into the form of combined sulfur (COS, and S0 and H s.) but practically all of which is in the form of sulfur vapor. 2.- The production of steam, by the combustion of the hydrogen of the hydrocarbons, and the decomposition of a portion of this steam, by the metal of the sulfid. 3. The combination of any H S and S0 which may be produced on account of inequalities in the operation of the furnace, or from other causes, in accordance with the welLknown reaction QH,S+SO =QH,O+3S, which sulfur will be carried along to the CO in accordance with thefollowing equa-- tion,

It may sometimes happen that the amount of steam produced by the combustion of the hydrocarbon gases, will be insuflicient, for the prevention of the formation of consider able amounts of S0 and when this is found i to be the case, it is readily overcome by the admission into the furnace of a suflicient amount of steam for the purpose. This admission of steam to the furnace chamber will not generally be necessary.

The substitution of the hydrocarbon gases in place of producer gas, possesses a material advantage, on account of the absence of nitrogen, which in producer gas acts as a diluent of the active portions of the gas, also the absence of large quantities of carbon monoxid with the tendency of this substance to unite with considerable amounts of the surfur of the ore under treatment, with the formation of COS, also the great efficiency of this gas as a' heating agent (this gas corresponds to about 1500 B. T. U. as compared with producer gas whichcorresponds to about 150 B. T. U.). Moreover this gas possesses the great advantage over producer gas that it carries a sufficient amount of hydrogen for the decomposition of the COS which will ordinarily be formed in operating the process. This gas.

also possesses material advantages over water gas, in the absence of CO in large quantities,

and also as being more efficient as a heating agent, and very much more easy to control the furnace conditions. fhis gas also possesses material advantages over the use of Y oil (crude oil or its distillates or still bottoms) in that the oil is more difficult to regulate. It is also extremely difficult when using oil, to produce a flame which is not open to the objection of being too hot, whereby the ore under treatment is liable to melt and sinter together. The described gas possesses great advantages over coal dust for these reasons, and also on ac count of the properties of the gas above referred to.

What I claim is 1. A process of distilling the sulfur of those varieties of sulfid ores, in which no considerable amount of sulfid having both fixed and feeble sulfur atoms exists,

said process comprising the treatment of a layer of said ore, with a reducing flame obtained by burning a gas mixture containing large amounts of methane and ethylene.

2. A process of distilling the sulfur of those varieties of sulfid ores, in which no considerable amount of sulfid 'having both fixed and feeble sulfur atoms exists, said process comprising thetreatment of a layer of said ore, with a reducing flame obtained by burning a gas mixture containing large amounts of methane and ethylene, while agitating said ore.

3. A process of distilling the sulfur of those varieties of sulfid ores, in which no considerable amount of sulfid having both fixed and feeble sulfur atoms exists, said process comprising the treatment of a layer of said ore,with a reducing flame obtained by burning a gas mixture containing large amounts of methane and ethylene, while maintaining the temperature in the reaction zone, between 700 and 900 C.

4. A process of distilling" the sulfur of those varieties of sulfid ores, in which no considerable amount of sulfid having both fixed and feeble sulfur atoms exists, said process comprising the treatment of a layer of said ore, with a reducing flame obtained by burning a gas mixture containing large amounts of methane and ethylene, and adding steam to the gases and vapors leaving the furnace.

5. A process of distilling the sulfur from pyrrhotite ore, which comprises exposing said ore to the action of steam and of a reducing flame produced by burning a gas mixture containing large amounts of methane and ethylene, while simultaneously agitating said ore.

6. A process of distilling the sulfur of those varieties of sulfid ores in which no considerable amount 'of sulfid having both fixed and feeble sulfur atoms exists, said process comprising the treatment of a layer of said ore, with a reducing flame obtained by burning a gas flame containing large amounts of hydrocarbons.

7. A process of distilling the sulfur from pyrrhotite ore, which comprises exposing said ore to the action of steam and of a re-' ducing flame produced by burning a gas mixture containing large amounts of hydrocarbons, while simultaneously. agitating said ore.

In testimony whereof I have affixed my signature, in presence of two witnesses.

WILLIAM A. HALL.

Witnesses A. B. FOSTER, A. M. PERKINS. 

